Vapor generator



Jan. 7, 1958 M. FRISCH VAPOR GENERATOR 5 Sheets-Sheet3 Filed Aug. 30. 1954 (Ittorneg Jan. 7, 1958 M. FRISCH 2,813,837

' I VAPOR GENEIIRATOR File d Aug. 50, 1954 5 Sheets-Sheetfi 3 nven to'r itorne Jim. 7, 1958 M. FRl S QH 3 9 VAPOR cE E RAToR 119 1 Aug? :50, 1954 I 5 Sheets-Sheet 5 C(ttorn eg United States Patent VAPOR GENERATOR Martin Frisch, New York, N. Y., assignor to Foster Wheeler Corporation, New York, N. Y., a corporation of New York Application August 30, 1954, Serial No. 452,946

11 Claims. (Cl. 122-240) The present invention relates to a vapor generator and more particularly to a multiple furnace vapor generator.

In a vapor generator having a superheater and a resuperheater, difficulty is encountered in maintaining desired superheated and resuperheated vapor temperatures when the quantity of saturated vapor produced by the vapor generator is varied. This is because the superheated vapor does not absorb the same amount of heat per pound of vapor flowing through it as the load varies from a predetermined value, and similarly, the temperature of the resuperheated vapor delivered to the resuperheater from the turbine changes as the load varies from such predetermined value. The temperature of the vapor delivered to the resuperheater from the turbine increases as the load increases.

In accordance with the present invention, a vapor generator is provided having a separate saturated vapor furnace, a separate superheater furnace, and a separate resuperheater furnace. Each furnace is provided with independently controlled firing means so that as the load varies from a predetermined value, the firing means can be controlled to obtain the desired superheated and resuperheated temperatures.

A characteristic of a radiant superheater is that it absorbs less heat per pound of vapor flowing through it when the quantity of saturated vapor produced by the vapor generator increases. Conversely, a convection superheater absorbs more heat per pound of vapor flowing through it when the quantity of saturated vapor produced by the generator increases.

In the present invention, radiant and convection superheaters are so arranged that the superheater characteristics complement one another and the superheated vapor temperature tends to remain constant as the quantity or load of saturated vapor produced in the vapor generator varies from the predetermined value. As a result of this superheater arrangement and differential firing of the supreheater furnace, the ratio of fuel required by the superheater furnace to the total fuel required by the vapor generator can be maintained substantially constant for any load of saturated vapor produced by the generator. Thus, in the present invention, the problem of controlling the superheated steam temperature is extremely simple.

As in the case of a radiant superheater, a radiant resuperheater or reheater similarly absorbs less heat per pound of vapor flowing through it when the quantity of saturated vapor output increases from the predetermined value. In the present invention, a radiant resuperheater is arranged in the vapor generator so that it will offset the increased temperature of the vapor delivered to the resuperheater from the turbine. As a result of'this arrangement and differential firing of the resuperheater furnace, the ratio of fuel required by the resuperheater furnace to the total fuel required by the generator can also be maintained substantially constant for any load of 2,818,837 Patented Jan. 7, 1958 saturated vapor produced by the generator. Thus, the control of the resuperheated vapor temperature is relatively simple.

The invention together with its various features and advantages will be better understood from the following description when considered in connection with the accompanying drawings forming a part thereof and in which:

Fig. 1 is a sectional view, in elevation, of a vapor generator embodying the present invention;

Fig. 2 is a plan view of the vapor generator of Fig. 1, partly broken away;

Fig. 3 is a diagrammatic and sectional view, in elevation, of a second embodiment of the invention similar to that shown in Fig. 1;

Fig. 4 is a section taken on the line 4-4 of Fig. 3;

Fig. 5 is a plan and sectional view of a third embodiment of the invention similar to that shown in Fig. 1;

Fig. 6 is a section taken on the line 6--6 of Fig. 5;

Fig. 7 is a section taken on the line 77 of Fig. 5;

Fig. 8 is a section taken on the line 8-8 of Fig. 5;

Fig. 9 is a plan and sectional view of a fourth embodiment of the invention similar to that shown in Fig. 1;

Fig. 10 is a section taken on the line 1010 of Fig. 9;

Fig. 11 is a section taken on the line 11-11 of Fig, 9; and

Fig. 12 is a sectional view taken on the line 1212 of Fig. 9.

Like characters of reference refer to the same parts throughout the several views.

Referring to Fig. 1 of the drawings, the reference numeral 10 designates the setting of a vapor generator which includes a front wall (not shown), a rear wall 11, opposite side walls 12 and 13, and a roof and a floor 14 and 15, respectively. The interior of the setting is divided into a resuperheating furnace 16, steam generating furnace 17, superheating furnace 18, and a gas passage 19. Water wall tubes 20 line the portion of rear wall 11 adjacent the furnaces and other water wall tubes (not shown), similar to tubes 20, line the portion of the front wall adjacent the furnaces. The upper and lower ends of tubes 20 are connected to headers 21 and 22, respectively. Header 21 communicates with a steam and water'drum 23 located above passage 19 by connecting tubes 24. Header 22 communicates with a downcomer tube 25 shown in broken lines) by connecting tubes 26. Downcomer 25 communicates with drum 23 by connecting tubes 27. The upper and lower ends of water wall tubes (not shown) lining the portion of the front wall (not shown) of the setting are connected to headers (not shown), similar to headers 21 and 22. These headers (not shown) communicate with drum 23 and downcorner 25 by connecting tubes (not shown) similar to the tubes communicating headers 21 and 22 with drum 23 and downcomer 25.

Resuperheater furnace 16 is positioned in the setting between well 12 and a row of substantially vertically extending and contacting water tubes 28 which. extend between the front and rear walls and in spacedrelationship with wall 12. A row of resuperheater tubes 29 line the portion of roof 14 between wall 12 and tubes 28,,the wall 12 and the downwardly inclined lower portion of furnace 16 extending toward wall 13 and adjacent tubes 28. Tubes 29 are connected at their upper ends to a. resuperheater inlet header 3%, positioned above roof 14, and are connected at their lower ends to resuperheater outlet header 31, disposed adjacent floor 15. Furnace 16 is fired by burners 32 disposed in roof 14.

Steam generating furnace 17 is disposed in the setting adjacent furnace 16 and between tubes 28 and a row of substantially vertically extending and contacting water tubes 36 which extend between the front and rear walls and in spaced relationship with tubes 28. The lower portions of tubes 28 are spaced laterally of one another in the setting to provide a gas opening 37 in resuperheater furnace 16 communicating with furnace 17. The portion of tubes 28, below opening 37, are downwardly inclined toward wall 13 and extend across the lower portion of furnace 17 to a point substantially adjacent tubes 36 and are connected to a header 38. The upper portion of tubes 28, adjacent roof 14, extend substantially horizontally to a point adjacent tubes 36 after which they extend above roof 14 and are connected to a header 39. Header 38 communicates with downcomer 25 by connecting tubes 40 while header 39 communicates with drum 23 by connecting tubes 41. Furnace 17 is fired by burners 42 disposed in roof 14.

Superheater furnace 18 is positioned in the setting between tubes 36 and a row of substantially vertically extending tubes consisting of superheater tubes 43, alternate superheater tubes 44' and 45 which extend across the setting between the front and rear walls. The lower portion of tubes 36 are spaced laterally of one another in the setting to provide a gas opening 44 communicating steam generating furnace 17 with superheater furnace 18. The portion of tubes 36, below opening 44, extend horizontally toward wall 12 and are spaced vertically of one another to provide an ash opening 46 for furnace 17. Opening 46 communicates with an ash outlet 47 in setting floor 15. The lower ends of tubes 36 are connected to header 38 and the upper ends are connected to header 39. The upper portion of superheater tubes 43, adjacent roof 14, extend horizontally toward wall 12 to a point adjacent tubes 36 after which they extend above roof 14 and are connected to drum 23. The upper ends of tubes 45 extend above roof 14 and are connected to a superheater header 49. The lower portions of tubes 43 and of alternate tubes 45 are spaced laterally of one another to provide a gas opening 48 communicating furnace 18 with gas passage 19. The portions of tubes 43 and of tubes 45 below opening 48 are downwardly inclined toward wall 12 and are in spaced relationship with tubes 36 to provide an ash outlet 50 for furnace 18. The lower ends of tubes 43 and 45 are connected to a superheater header 51. Furnace 18 is fired by burners 48 disposed in roof 14.

Gas passage 19 is located in the setting, adjacent furnace 18, between the row of tubes consisting of superheater tubes 43, alternate superheater tubes 44' and 45, and side wall 13. A two section economizer 52 is disposed in the upper portion of passage 19 above an extended surface boiler section 53. The inlet of economizer 52 communicates with drum 23 by connecting tubes 54, and the outlet of the economizer communicates with a dual circulation drum 55 above passage 19, by a downcomer 56 and connecting tubes 57. Drum 55 communicates with drum 23 by upper and lower connecting tubes 58 and 59, respecitvely. Boiler section 53 is connected to downcomer 56, and to drum 55 by connecting tubes 60. A bare tube boiler section 61 is disposed in the lower portion of passage 19 above a convection superheater 62. Boiler section 61 communicates with drum 55 by a downcomer 63 (partly shown in Fig. 1) and by connecting tubes 64 which extend upwardly in passage 19, adjacent furnace 18, to said drum. Convection superheater 62 is provided with a superheater outlet 65 and a superheater inlet 65 which is connected to radiant superheater outlet header 49 by tubes 44'.

In operation, when the vapor generator is fired, the gases in resuperheater furnace 16 pass downwardly therein in heat exchange relationship with radiant resuperheater tubes 29 and thereafter pass through opening 37 into the lower portion of furnace 17. The gases in steam generating furnace 17 pass downwardly therein in heat exchange relationship with steam generating or water tubes 28 and 36 and thereafter pass through opening 44 into. the lower portion of furnace 18. The gases in furnace 18 pass downwardly therein in heat exchange relationship with superheater tubes 43 and alternate superheater tubes 44' and 45. Thereafter, the gases from the furnaces commingle and pass through opening 48 into gas passage 19 and flow upwardly therein in heat exchange relationship with convection superheater 62, bare tube boiler section 61, extended surface boiler section 53 and economizer 52. The gases then flow out of the upper end of passage 19 through a gas outlet 66 to a stack (not shown).

In the present invention, when the quantity or load of saturated steam generated in furnace 17 increases, the heat absorbed per pound of steam flowing through radiant superheater tubes 43, 44 and 45, decreases since a radiant superheater absorbs less heat per pound of steam flowing through it as the steam load produced in the vapor generator increases. Conversely, the heat absorbed per pound of steam flowing through convection superheater 62 increases as the steam load of the vapor generator in creases. Thus, the radiant superheater and convection superheater complement one another and the superheated steam temperature leaving superheater outlet and flowing to a turbine (not shown) tends to remain constant. As a result of this superheater arrangement and the differential firing of the superheater furnace, the ratio of fuel required by the superheater furnace to the total fuel required by the vapor generator is maintained substantially constant for any load of saturated vapor produced in the vapor generator.

When the quantity of saturated steam generated in furnace 16 is increased, the temperature of the steam delivered to resuperheater inlet header 30 from a turbine (not shown) increases. Since it is a characteristic of a radiant resuperheater that less heat is absorbed per pound of steam flowing through it as the steam load produced in the vapor generator is increased, resuperheater tubes 29 absorb less heat and compensate for the increased temperature of the steam delivered to the resuperheater from the turbine. Thus, the resuperheater steam temperature leaving resuperheater outlet 31 tends to remain constant with variations in the load of saturated steam produced. As a result of this resuperheater arrangement and the differential firing of the resuperheater furnace, the ratio of fuel required by the resuperheater furnace to the total fuel required by the vapor generator is maintained substantially constant for any load of saturated vapor produced in the vapor generator.

The embodiment of the invention shown in Figs. 3 and 4 is substantially the same as that shown in Figs. 1 and 2, except that the superheater furnace 70 is disposed in the upper portion of the setting, and the gas passage 71 is disposed in the lower portion of the setting below said superheater furnace.

Water wall tubes 72 (Fig. 4) are positioned in the resuperheater furnace between resuperheater tubes 29. Tubes 72 are connected at their upper ends to a stem drum 73 and at their lower ends to header 38. The row of water wall tubes 74 separating steam generating furnace 17 from superheater furnace 70 are spaced laterally of one another adjacent the lower portion of furnace 70 to provide'a gas opening 75 between said furnaces. Radiant superheater 76 is a single pass type superheater and comprises a row of superheater tubes 77 the lower portions of which are downwardly inclined toward opening 75 and extend to a point substantially adjacent said opening. The lower ends of tubes 77 are connected to a convection superheater 78 which is disposed in the lower portion of passage 71. Steam generating surface 79 (Fig. 3) of a waste heat boiler 80 (Fig. 3) is located in the upper portion of passage 71 above superheater 78. Surface 79 communicates with waste heat boiler drum 82 by con necting tubes 83 and 84. A gas outlet 85 is provided in the upper portion of passage 71 and communicates with a stack (not shown).

i In operation, the embodiment of the invention shown in Figs. 3 and 4 is substantially the same as the invention illustrated in Figs. 1 and 2, except that combustion gases from superheater furnace flow through gas opening into the steam generating furnace and join the gases therein, and the gases which enter furnace 17 from the resuperheater furnace 16. Thereafter, the gases flow into gas passage 71 and pass in heat exchange relationship with convection superheater 78 and waste boiler surface 79 before passing out the passage through outlet 85.

The embodiment of the invention shown in Figs. 5 to 8 is similar to that shown in Fig. 1, except that resuperheater furnace (Figs. 5 and 6), steam generating furnace 91 (Figs. 5 and 7), and superheater furnace 92 (Figs. 5 and 8) extend across the setting between side wall 12 and gas passage 93. Gas passage 93 is provided with a portion 94 which extends across the setting between the front and rear walls and is positioned below the ends of the furnaces adjacent passage 93. Resuperheater furnace 90 is located adjacent rear wall 11 (Fig. 5) and is separated by a row of water wall tubes 95 (Fig. 5 from steam generating furnace 91. Water wall 95 (Fig. 5) extends across the setting between side wall 12 and passage 93. Furnace 91 is separated by a row of water wall tubes 96 (Fig. 5) from superheater furnace 92. Water wall 96 extends across the setting between side wall 12 and passage 93. The furnaces are separated from passage 93 and passage portion 94 by a row of water wall tubes 97. Tubes 97 extend across the setting between the front and rear walls. The lower portions of tubes 97 are downwardly inclined toward setting wall 12 above passage portion 94 and thereafter extend across said passage portion and then downwardly in the setting. Tubes 97 are spaced vertically of one another in the passage to permit flow of v gases therethrough.

Rows of resuperheater tubes 98 and 99 (Figs. 5 and 6) are positioned across furnace 90 between rear wall 11 and water wall 95. Tubes 98 and 99 are spaced an equal distance from side wall 12 and water wall 97, respectively, and are spaced an equal distance from each other, to divide the furnace into three equally proportioned furnace sections 100, 101, and 102 (Figs. 5 and 6). The lower portion of resuperheater tubes 98 are spaced laterally of one another to provide a gas opening 98' (Fig. 6) between sections 100 and 101. The lower portions of resuperheater tubes 99 are spaced laterally of one another adjacent the lower portion of section 102 to provide a gas opening 99 (Fig. 6) between sections 101 and 102. Each furnace section is provided with a burner disposed in the setting roof. i

Rows of water wall tubes 103 and 104 (Figs. 5 and 7) are positioned across furnace 91 between water walls 95 and 96 and in alignment with resuperheater 'tube rows 98 and 99 and divide the furnace into sections 105, 106 and 107 (Figs. 5 and 7). tubes 103 are spaced laterally of one another to provide a gas opening 103 (Fig. 7) between furnace sections and 106. The lower portions of water wall tubes 104 are spaced laterally of one another adjacent the lower portion of section 107 to provide a gas opening 104 (Fig. 7) between sections 106 and 107. Each furnace section is provided with a burner disposed in the setting roof.

Rows of superheater tubes 108 and 109 (Figs. 5 and 8) are positioned across furnace 92 between water wall 96 and the setting front wall and in alignment with water walls 103 and 104 and divide the furnace into sections 110, 111 and 112.

The lower portion of tubes 108 are spaced laterally of one another to provide a gas opening 108 (Fig. 8) between furnace sections and 111. The lower portion of tubes 109 are spaced laterally of one another adjacent.

The lower portion of water wall 4 6 connected to a superheater outlet header 113 (Fig. 8). Header 113 communicates with an inlet header 115 of a convection superheater 116 by connecting tubes 114 (Fig. 8). Convection superheater 116 is disposed in portion 94 of gas passage 93.

Gas passage 93 is provided with a bank of steam generating tubes 118. Tubes 118 are connected at their upper ends to steam drum 119 and at their lower ends to water drum 120 in alignment with said upper drum. A gas passage 121 is provided between water wall tubes 97 and tube bank 118 by a bafiie 122 which extends across passage 93 between the setting front and rear walls. Bafile 122 extends vertically between lower drum 120 to a point in spaced relationship with drum 119 to provide a gas opening 123 in communication with passage 121 and tube bank 118. Gas passage 93 is provided with a gas outlet 124 in communication with a stack (not shown).

In operation, when the burners are fired, combustion gases in furnace sections 100 and 102 of resuperheater furnace 90 flow into the middle furnace section 101 and join the gases in said section after which all the gases flow into portion 94 of gas passage 93 adjacent the rear wall of the setting. Combustion gases in furnace sections 104 and 105 of steam generating furnace 91 pass into the middle furnace section after which the gases from the three sections flow into portion 94 of gas passage 93 intermediate the rear and front wall of the setting. Combustion gases in furnace sections 110 and 112 of superheater furnace 92 flow into middle furnace section 111 and thereafter the gases from the three furnace sections flow in portion 94 of gas passage 93 adjacent the front wall of the setting. The gases in portion 94 pass upwardly in heat exchange relationship with superheater 116 and thereafter flow upwardly in gas passage 121. The gases pass through opening 121 into tube bank 118 flowing downwardly therein in heat exchange relationship with said tubes after which the gases pass out of passage 93 through gas outlet 124.

The embodiment of the invention illustrated in Figs. 9 to 12 is substantially the same as the embodiment of the invention shown in Figs. 5 to 8, except that resuperheater furnace 130, steam generating furnace 131, and superheater furnace 132 are divided into two furnace sections instead of three. A row of resuperheater tubes 137 (Figs. 9 and 10) divides furnace into two equally proportioned furnace sections 135 and 136 (Figs. 9 and 11). A row of water wall tubes 138 (Figs. 9 and 11) divides furnace 131 into equally proportioned furnace sections 139 and 140 (Figs. 9 and 11), and a row of superheater tubes 141 (Figs. 9 and 12) divides furnace 132 into equally proportioned furnace sections 142 and 143 (Figs. 9 and 12). Also, the gas passage 144 of the present embodiment of the invention extends vertically of the setting between the roof and floor. An economizer 14S and primary air heater 146 are disposed in the upper portion of passage 144, while a boiler tube section 147 is positioned in the lower portion, above convection superheater 148. A gas outlet 149 is provided in the upper portion of the passage in communication with a stack (not shown). The vapor generators steam and water drum 150 is located above passage 144.

In operation, the embodiment of the invention in Figs. 9 to 12 is substantially the same as that shown in Figs. 5 to 8. Combustion gases in furnace section 135 flow into furnace section 136 of resuperheater furnace 130 and join the combustion gases therein, the gases thereafter passing into gas passage 144. Combustion gases in furnace section 139 flow into furnace section 140 of steam furnace 131 and join the combustion gases therein, the gases thereafter passing into gas passage 144. Gases in section 142. of superheater furnace 132 join the gases produced in furnace section 143 after which they flow in passage 144. In passage 144, the gases flow upwardly therein in heat exchange relationship with superheater 148, boiler tube section 147, economizer and primary 7 air heater 146. The gases pass out of the top of the passage through outlet 149 to a secondary air heater, not shown.

Inasmuch as changes may be made in the form, location and relative arrangement of the several parts of the apparatus disclosed without departing from the essential characteristics of the invention, it will be understood that the invention is not to be limited excepting by the scope of the appended claims.

What is claimed is:

1. A vapor generator having a vapor-liquid drum, comprising a setting having four contiguous walls and a gas outlet, a vapor generating furnace, superheater furnace, and resuperheater furnace disposed in said setting, said vapor generating furnace comprising spaced banks of vapor generating tubular members arranged to define a chamber therebetween; said superheater furnace comprising spaced banks of vapor generating tubular members, and at least one bank of superheating tubular members, said banks of vapor generating tubes and bank of superheating tubes being arranged in relationship with each other to define a chamber therebetween; said resuperheater furnace comprising spaced banks of vapor generating tubular members, at least one bank of resuperheating tubular members, said banks of vapor generating tubes and said bank of resuperheating tubes being arranged in relationship with each other to define a chamber therebetween, means for separately fuel firing each of said furnaces to produce combustion gases in each of the furnace chambers, each of said furnaces having a gas outlet, gas passage means in communication with said furnace gas outlets and the setting gas outlet to respectively receive combustion gases from the furnace gas outlet of each furnace and to conduct the combustion gases to said setting gas outlet, and a superheater member disposed in said gas passage means in heat exchange relationship with. the combustion gases fiowing therethrough, said vapor generating tubular members communicating with the vapor-liquid drum to receive liquid therefrom and pass the liquid in heat exchange relationship with the heat generated by fuel combustion in the vapor generating furnace to vaporize at least some of said liquid and to deliver the vapor and liquid to said vaporliquid drum, said bank of superheater tubular members being in communication with the vapor-liquid drum and the superheater member to respectively receive vapor from the vapor-liquid drum and pass the vapor in heat exchange relationship with heat generated by fuel combustion in the superheater furnace and to deliver heated vapor to the superheater member, said bank of resuperheater tubular members being adapted to receive relatively cool vapor and to pass the vapor in heat exchange relationship with heat generated by fuel combustion in the resuperheater furnace.

2. A vapor generator having a vapor-liquid drum, comprising a setting having four contiguous walls and a gas outlet, a vapor generating furnace comprising spaced banks of first vapor generating tubes disposed within said setting and arranged to define a chamber therebetvveen; a superheater furnace comprising spaced banks of second vapor generating tubes, one of the banks of first vapor generating tubes, and at least one bank of superheating tubes, said bank of superheating tubes and said banks of first and second vapor generating tubes being disposed within the setting and in relationship to each other to define a chamber therebetween; a resuperheater furnace comprising spaced banks of third vapor generating tubes, another one of said banks of first vapor generating tubes of the vapor generating furnace, and at least one bank of resuperheating tubes, said bank of resuperheater tubes and said banks of first and third vapor generating tubes being disposed within the setting and in relationship to each other to define a chamber therebetween, means for separately fuel firing each of said furnaces to produce combustion gases in each of said furnace chambers, each a 8 of said furnaces having a combustion gas outlet, combustion gas passage means in communication with said furnace gas outlets and the setting gas outlet to respectively receive combustion gases from the furnace gas outlets and to conduct the combustion gases to said setting gas outlet, and a superheater member disposed in said gas passage means in heat exchange relationship with the combustion gases flowing therethrough, said first, second and third vapor generating tubes communicating with the vapor'liquid drum to receive liquid therefrom and pass the liquid in heat exchange relationship with the heat generated by fuel combustion in each of said furnaces to vaporize at least some of said liquid and to deliver the vapor and liquid to said vapor-liquid drum, said superheater tubes being in communication with the vapor-liquid drum and the superheater member to respectively receive vapor from the vapor-liquid drum and pass the vapor in heat exchange relationship with the heat generated by fuel combustion in the superheater furnace and then to deliver the heated vapor to the superheater member, said bank of resuperheater tubes being connected to receive relatively cool vapor and to pass the vapor in heat exchange relationship with heat generated by fuel combustion in the resuperheater furnace.

3. In the vapor generator of claim 2 wherein the first, second and third vapor generating tubes and the superheater and resuperheater tubes extend substantially vertically in said setting.

4. In the vapor generator of claim 2 wherein the tubes of at least one of the bank of tubes defining each of the furnaces are displaced from each other to provide a combustion gas outlet in each furnace.

5. A vapor generator having a vapor-liquid drum, comprising a setting having two pair of opposite walls and a gas outlet, a vapor generating furnace centrally disposed in said setting, said vapor generating furnace comprising spaced banks of first vapor generating elements arranged to define therebetween a chamber, a superheater furnace disposed in said setting adjacent said vapor generating furnace, said superheater furnace comprising at least one bank of superheating elements arranged in relationship with one of said spaced banks of first vapor generating elements of the vapor generating furnace and spaced banks of second vapor generating elements to define a chamber therebetween; a resuperheater furnace disposed in said setting adjacent said vapor generating furnace chamber opposite from said superheating furnace, said resuperheater furnace comprising at least one bank of resuperheater elements arranged in relationship with another bank of said banks of first vapor generating tubes of said vapor generating furnace chamber and spaced banks of third vapor generating elements to define at least one chamber therebetween, means for separately fuel firing each of said furnaces to produce combustion gases in each of the furnace chambers, each of said furnaces having a gas outlet, gas passage means in communication with said furnace gas outlets and the setting gas outlet to respectively receive combustion gases from the furnace gas outlets and to conduct the combustion gases to said setting gas outlet, and a superheater member disposed in said gas passage means in heat exchange relationship with the combustion gases flowing therethrough, said banks of first, second and third vapor generating elements being in communication with said vapor-liquid drum to receive liquid therefrom and pass the liquid in heat exchange relationship with the heat generated by fuel combustion in the furnace chambers to vaporize at least some of said liquid and to deliver the vapor to said vapor-liquid drum, said bank of superheater elements being in communication with the vapor-liquid drum and the superheater member to respectively receive vapor from the vaporliquid drum and pass the vapor in heat exchange relationship with heat generated by fuel combustion in the superheater furnace and to deliver heated vapor to the superheater member, said bank of resuperheater elements being 9 connected to receive relatively cool vapor and pass the vapor in heat exchange relationship with heat generated by fuel combustion in the resuperheater furnace.

6. A vapor generator having a vapor-liquid drum, comprising a setting having side and end Walls and a gas outlet, two spaced rows of vapor generating tubes disposed in the setting in spaced relationship with the side walls to define three chambers within said setting, said spaced rows of vapor generating tubes defining therebetween a vapor generating furnace chamber, a row of superheater tubes disposed adjacent one of said side walls and spaced from one of said rows of vapor generating tubes to define a superheater furnace chamber therebetween, a row of resuperheater tubes disposed adjacent the other side wall and spaced from the other row of vapor generating tubes to define a resuperheater furnace chamber therebetween, separately fired fuel burner means for each of said furnace chambers for producing combustion gases in each of said furnace chambers, a combustion gas outlet for each of said furnace chambers, a gas passage means in communication with furnace chamber outlets and said setting gas outlet to receive all of the combustion gases from said furnace chambers and to conduct the combustion gases to said setting gas outlet, and a convection superheater disposed in said gas passage means in heat exchange relationship with said combustion gases flowing there:

through, said vapor generating tubes being in communication with the vapor-liquid drum to receive liquid therefrom and pass the liquid in heat exchange relationship with heat generated by fuel combustion in said vapor generating furnace, superheater furnace and the resuperheater furnace to vaporize at least some of said vapor and to deliver vapor and liquid to the vapor-liquid drum, said superheater tubes communicating with said vapor-liquid drum and said convection superheater to respectively receive vapor from said vapor-liquid drum and pass the vapor in heat exchange relationship with heat generated by fuel combustion in the superheater furnace chamber and to deliver heated vapor to the convection superheater, said resuperheater being connected to receive relatively cool vapor and adapted to pass the vapor in heat exchange relationship with the heat generated by fuel combustion in said resuperheater furnace chamber.

7. A vapor generator having a vapor-liquid drum, comprising a setting having side and end walls and a gas outlet, two spaced rows of vapor generating tubes disposed in the setting in spaced relationship with the side walls to define three chambers within said setting, said spaced rows of vapor generating tubes defining therebetween a vapor generating furnace chamber, a row of superheater tubes disposed adjacent one of said side walls and spaced from one of said rows of vapor generating tubes to define a superheater furnace chamber therebetween, a row of resuperheater tubes disposed adjacent the other side wall and spaced from the other row of vapor generating tubes to define a resuperheater furnace chamber therebetween, separately fired fuel rburner means for each of said furnace chambers for producing combustion gases in each of said furnace chambers, a portion of the vapor generating tubes of each of said rows of vapor generating tubes being displaced from each other to provide a combustion gas outlet for said resuperheater furnace chamber and said vapor generating furnace, a portion of the superheater tubes being displaced from each other to provide a combustion gas outlet for the superheater furnace chamber, a gas passage means in communication with the furnace gas outlets and said setting gas outlet to receive all of the combustion gases from said furnace chambers and to conduct the combustion gases to said setting gas outlet, and a convection superheater disposed in said gas passage means in heat exchange relationship with said combustion gases flowing therethrough, and a convection superheater disposed in said gas passage means in heat exchange relationship with said combustion gases flowing therethrough, said vapor generating tubes being in communication with the vapor liquid drum to receive liquid therefrom and passthe liquid in heat exchange relationship with heat generated by fuel combustion in said vapor generating furnace, superheater furnace and the resuperheater furnace to vaporize at least some of said vapor and to deliver vapor and liquid to the vapor-liquid drum, said superheater tubes communicating with said vapor-liquid drum and said convection superheater to respectively receive vapor from said vapor-liquid drum and pass the vapor in heat exchange relationship with heat generated by fuel combustion in the superheater furnace chamber and to deliver heated vapor to the convection superheater, said resuperheater being connected to receive relatively cool vapor and adapted to pass the vapor in heat exchange relationship with the heat generated by the fuel combustion in said resuperheater furnace chamber.

8. A vapor generator having a vapor-liquid drum, comprising a setting having side and end walls and a gas outlet, two spaced rows of vapor generating tubes disposed in spaced relationship with the side walls of the setting, said spaced rows of vapor generating tubes defining therebetween a vapor generating furnace chamber, a row of superheater tubes disposed adjacent one of said side walls and spaced from one of said rows of vapor generating tubes to define a superheater furnace chamber therebetween, a row of superheater tubes disposed adjacent the other side wall and spaced from the other row of vapor generating tubes to define a resuperheater furnace chamber therebetween, a separately fired fuel burner means for each of said furnace chambers for producing combustion gases in each of said furnace chambers, a combustion gas outlet in each of said furnace chambers, a gas passage means disposed below said superheater furnace chamber and in communication with the furnace chamber outlets and said setting gas outlet to respectively receive all of the combustion gases from said furnace chambers and conduct the combustion gases to said setting gas outlet, and a convection superheater disposed in said gas passage means in heat exchange relationship with said combustion gases flowing therethrough, said vapor generating tubes being in communication with the vapor liquid drum to receive liquid therefrom and pass the liquid in heat exchange relationship with heat generated by fuel combustion in said vapor generating furnace, superheater furnace and the resuperheater furnace to vaporize at least some of said vapor and to deliver vapor and liquid to the vapor-liquid drum, said superheater tubes communicating with said vapor-liquid drum and said convection superheater to respectively receive vapor from said vapor-liquid drum and pass the vapor in heat exchange relationship with heat generated by fuel combustion in the superheater furnace chamber and to deliver heated vapor to the convection superheater, said resuperheater being connected to receive relatively cool vapor and adapted to pass the vapor in heat exchange relationship with heat generated by fuel combusion in said resuperheater furnace chamber.

9. An upright vapor generator having a vapor-liquid drum, comprising a setting having side and end walls and a gas outlet, two spaced rows of vertically extending vapor generating tubes disposed in spaced relationship with the side walls of the setting, said spaced rows of vapor generating tubes defining therebetween a vapor generating furnace chamber, a row of vertically extending superheater tubes extending adjacent to and parallel to one of the side walls at the upper portion thereof and at the lower portion extending inwardly to the adjacent row of vapor generating tubes to define a superheater furnace chamber and a gas passage below the superheater furnace chamber, said gas passage being in communication with said setting gas outlet, a row of vertically extending resuperheater tubes extending adjacent to and parallel to the other side wall of the setting and in spaced relationship with the other row of vapor generating tubes to define a resupcrheater furnace chamber therebetween, a separately fired fuel burner means for eachof said furnace chambers for producing combustion gases in each of said furnace chambers, a combustion gas outlet for each of said furnace chambers communicating with the gas passage to pass combustion gases from the furnace chambers to the gas passage, and a convection superheater disposed in the gas passage in heat exchange relationship with the combustion gases flowing through the gas passage, said vapor generating tubes being in communication with the vapor-liquid drum to receive liquid therefrom and pass the liquid in heat exchange relationship with heat generated by fuel combustion in said vapor generating furnace chamber, superheater furnace chamber and the resuperheater furnace chamber to vaporize some of said vapor and to deliver vapor and liquid to the vapor-liquid drum, said superheater tubes communicating with said vapor-liquid drum to receive vapor therefrom and pass the vapor in heat exchange relationship with the heat generated by fuel combustion in the superheater furnace chamber and in communication with the convection superheater to deliver heated vapor to the latter, said resuperheater being connected to receive rela tively cool vapor and adapted to pass the vapor in heat exchange relationship with the heat generated by fuel combustion in said resuperheater furnace chamber.

10. A vapor generator having vapor-liquid drum, com prising a setting having side walls and end walls and a gas outlet, a row of first vapor generating tubes extending between said end Walls and adjacent to one of said side walls, two rows of second vapor generating tubes extending from the other of said side Walls to said row of first vapor generating tubes and in spaced relationship with said end walls to thereby divide the setting into three chambers, two spaced rows of superheater tubes extending across one of said chambers in spaced relationship with said row of first vapor generating tubes and said other side wall to divide the chamber into three superheater furnace sections, two spaced rows of third vapor generating tubes extending across another one of said chambers in spaced relationship with the row of first vapor generating tubes and said other side wall to divide the chamber into three vapor generating furnace sections, two spaced rows of resuperheater tubes extending across the remaining chamber in spaced relationship with the row of first vapor generating tubes and said other side Wall to divide the chamber into three resuperheater furnace sections, separately fired burner means for each of said furnace sections for producing combustion gases therein, each of said furnace sections having a combustion gas outlet, means forming a gas passage in communication with said furnace section combustion gas outlets and the setting gas outlet to respectively receive the combustion gases from the furnace sections and to deliver all the combustion gases to said setting gas outlet and a convection superheater disposed in the gas passage in heat exchange relationship with the combustion gases flowing through said gas passage, said first, second and third vapor generating tubes being in communication with said vapouliquid drum to receive liquid therefrom and pass the liquid in heat exchange relationship with the heat generated by fuel combustion in the vapor generating sections and superheater and reheater furnace sections to at least vaporize part of said liquid and to deliver vapor and liquid to said vapor-liquid drum, said superv 12 heater tubes being in communication with said vaporliquid drum to receive vapor therefrom and pass the vapor in heat exchange relationship with the heat generated by fuel combustion in the superheater furnace sections and in communication with the convection superheater to deliver heated vapor thereto, said resuperheater tubes being connected to receive relatively cool vapor and pass the vapor in heat exchange relationship with heat generated by fuel combustion in the resuperheater furnace sections.

ll. A vapor generator having a vapor-liquid drum, comprising a setting having side walls and end walls and a gas outlet, a row of first vapor generating tubes extending between said end walls and adjacent to but spaced from one of said side Walls to define with said adjacent side wall a gas passage, said gas passage being in communication with said setting gas outlet, two rows of spaced second vapor generating tubes extending from the other of said side walls to said row of first vapor generating tubes and in spaced relationship with the end walls to thereby divide the setting into three chambers, a row of superheater tubes extending across one of said chambers in spaced relationship with said row of first vapor generating tubes and said other side wall to divide the chamber into two superheater furnace sections, a row of third vapor generating tubes extending across another one of said chambers in spaced relationship with the row of first vapor generating tubes and said other side wall to divide the chamber into two vapor generating furnace sections, a row of resuperheater tubes extending across the remaining chamber in spaced relationship with the row of first vapor generating tubes and said other side wall to divide the chamber into two resuperheater furnace sections, separately fired burner means for each of said furnace sections for producing combustion gases therein, each of said furnace sections having a combustion gas outlet, said furnace section combustion gas outlets being in communication with said gas passage to pass combustion gases to said passage, and a convection superheater disposed in said gas passage in heat exchange relationship with combustion gases therein, said first, second and third vapor generating tubes being in communication with the vapor-liquid drum to receive liquid from the latter and pass the liquid in heat exchange relationship with heat generated by fuel combustion in said vapor generating furnace sections to at least partially vaporize the liquidand then to pass the vapor and liquid to said vapor-liquid drum, the superheater tubes being in communication with the vapor-liquid drum to receive vapor therefrom and pass the vapor in heat exchange relationship with heat generated by fuel combustion in the superheater furnace sections and in communication with the convection superheater to pass heated vapor thereto, said resuperheater tubes being connected to receive relatively cool vapor and adapted to pass the vapor in heat exchange relationship with heat generated by fuel combustion in the superheater furnace sections.

References Cited in the file of this patent UNITED STATES PATENTS 2,285,442 Kerr June 9, 1942 2,366,717 Frisch Jan. 9, 1945 2,737,160 Armacost et al Mar. 6, 1956 FOREIGN PATENTS 746,112 Germany June 10, 1944 

